It was a reluctant process, but they started with banning the selling of Indulgences and the worshiping of relics. Also, mass was conducted in Latin, Instead of the vernacular. Priests were taken through a "refreshing course" as you might call it, to reform their teaching. And lastly, there was the inquisition, to make sure all Catholics were faithfull. hope that helps! please vote this answer the branliest, too!
